FDA indicates support for Biogen ALS drug ahead of AdComm meeting

With an FDA advisory committee panel scheduled to meet on Wednesday to discuss whether to recommend accelerated approval of Biogen’s amyotrophic lateral sclerosis treatment, agency briefing documents leaned towards a positive opinion. 

The Peripheral and Central Nervous System Drugs Advisory Committee panel will be tasked with examining mixed evidence from a trial related to tofersen’s effectiveness and safety. 

Tofersen is an antisense oligonucleotide that works by blocking the production of the SOD1 protein, which clumps together with copies of itself and damages the nervous system. If approved, the drug could become the first to target a genetic cause of ALS.

In the briefing documents posted ahead of the meeting, the FDA reminded the panel that in the "setting of a very rare, life-threatening disease with significant unmet need, it is appropriate to exercise regulatory flexibility in applying the statutory standards for establishing effectiveness."

FDA staff also point out that despite this being a "situation where there is a negative clinical study that failed to show a statistically significant treatment effect in the prespecified primary analysis population," data from that study "indicate target engagement of the therapy and a reduction in a biomarker that has been shown to be correlated with disease progression and prognosis in patients with ALS."

The trial in question is the 28-week phase 3 VALOR study. Back in Oct. 2021, Biogen revealed that tofersen proved no better than a placebo at slowing progression in the trial. However, the drugmaker touted positive trends, celebrating a reduction of SOD1 protein, reduction of neurofilament, a potential biomarker for neurodegenerative disease, and positive signals across multiple key endpoints.

Back in Oct. 2022 the FDA extended its review period for Biogen's NDA, pushing the PDUFA date to April 25, 2023.